onan 5500 generator problems

[nas6car]

generator driving me nuts. always well maintained, but now having issues. flash code not helping me. replaced fuel and filters and added seafoam to the tank. it will run for 10 minutes, sometimes up to 1 hour with smooth idle and then just shut off. it seems like something is getting hot and opening a contact. it will not start back up for about 15 minutes and then same thing. I don't think its a fuel pump or carb issue. seems more like coil or internal short. can anyone help me please. p.s. bought Honda 2000 backup genny for now seemed like cheaper fix.

[DryCamper11]

nas6car wrote:
installed onan fuelpump, filter and bypass kit. did the trick thanks for all of your help

Congrats!

[nas6car]

installed onan fuelpump, filter and bypass kit. did the trick thanks for all of your help

[DryCamper11]

Handbasket wrote:
I was able to easily diagnose a failed fuel pump on my Onan

My Onan OEM fuel pump also failed, until I cleaned it. Not bad for 40 years old. Then I had a spare 🙂

[Handbasket]

FWIW, I was able to easily diagnose a failed fuel pump on my Onan 2800. Changing the fuel filter didn't help, so I let it run until it shut off. Then I pulled the fuel line off the carb inlet. Sure enough, dry on both sides. I replaced the pump (PITA!) and it ran fine until the voltage regulator failed a year+ later.

Jim, "Diagonally parked in a parallel universe."

[Y-Guy]

Moving from Toy Haulers to Tech Issues.

[DryCamper11]

My manual list says the HGJAB spec C needs the 983-00501C manual. I have the 983-00501D, not 983-00501C, but it seems to say it covers your machine. It would help to know the codes for when it stops after a half hour, and the code for a failed start (you said it won't start after it stops.) A bad coil or a bad fuel pump are both reasonable possibilities, but I think you'll need to test them during that period of time just after it fails, when it won't start.
Here's the D manual if you want it:
http://www.cumminsonan.com/www/pdf/manuals/983-0501D.pdf

[DryCamper11]

nas6car wrote:
thanks drycamper11 themode number is 5.5hgjab-5900d spec d, I cannot even locate the coil. is it internal? its definetly a split crowd, most of my friends say fuel pump or carb, I ruling out carb, just thought I would throw this at the experts before opening up wallet, thanks for your help.

That's a pretty recent model. I'll check my manuals, but it may be too new for me. I've got parts manuals , operating manuals, engine manuals and genset service manuals for all Onans stretching back 40+ years, but they stop in the early 2000's. If you don't get help here (I'll let you know what I find in my manuals), I strongly suggest you go to Smokstak.com and ask in the Onan forum. Those guys really know everything there is to know about Onans.

BTW, what code are you getting?

[nas6car]

serial number is lo60001990 then a bunch of other numbers- specd c186-2 5.5 hgjab-60 hgjab.... options r086-2 a223-1 c162-2 thanks

[nas6car]

thanks drycamper11 themode number is 5.5hgjab-5900d spec d, I cannot even locate the coil. is it internal? its definetly a split crowd, most of my friends say fuel pump or carb, I ruling out carb, just thought I would throw this at the experts before opening up wallet, thanks for your help.

[DryCamper11]

I had a 6.5 NHD Onan that would shut down after a while. It turned out to be a cracked solder joint on the control board.

[2wheelglider]

Onan has problems with fuel pumps getting hot and shutting down. Had the same problem last week. Would run for 30 seconds to no longer than an hour. Replaced with low pressure generic fuel pump from napa for $50 and problem solved.

[DryCamper11]

Post the dataplate model and serial number (or model and spec code at least). It's very hard to give you much info without knowing which Onan 5.5 KW you have.

For most models, this will tell you if it's the coil - disconnect a plug wire, connect a spare plug, touch the plug base to the engine and press the start button, then release it. It should spark at least once. If it's sparking multiple times, then it's a gas or air problem. If it sparks only once, when you release the start button, the coil is working and it's something else.

If no spark (for most Onans), it's the coil. To be sure, measure voltage at the coil. If you get 12V on then off and no spark, it's definitely the coil.